Bittern is a town on the Mornington Peninsula in Melbourne, Victoria, Australia, 61 km south-east of Melbourne's Central Business District, located within the Shire of Mornington Peninsula local government area. Bittern recorded a population of 4,276 at the 2021 census. Bittern is part of an urban enclave on Western Port comprising Bittern, Hastings, Crib Point, Somerville, and Tyabb.